But Mayor Jim Watson said it would cost the city an estimated $350,000 to build a new winter shelter for the Royal Swans, which are related to six pairs of mute swans gifted to Ottawa by the Queen in 1967 to mark Canada's centennial. The city wouldn't be able to handle that cost alone.

"They're a beautiful addition to the river, but we also have to make sure that we're not going to bring something that is going to be so expensive that public support for it vanishes," Watson said, releasing the birds on Thursday into the Rideau River for the summer.

October deadline

City staff are trying to secure private sponsorship, with a deadline of October.

Mark Taylor, the city councillor responsible for the royal swans, said failure to raise the funds might mean the end of the swan program altogether.

"I mean, if we get to that point that we've exhausted the options for private-sector partnership with this, then, you're right, we're going to have to make a decision," Taylor said.

One way or another, councillors agreed the swans' futures must be settled by the fall.